/*
 * Alloy Analyzer 4 -- Copyright (c) 2006-2008, Felix Chang
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package edu.ut.ece382c.valloy.ast;

import edu.mit.csail.sdg.alloy4.Pos;
import edu.mit.csail.sdg.alloy4.Err;
import edu.mit.csail.sdg.alloy4.JoinableList;
import static edu.ut.ece382c.valloy.ast.Type.EMPTY;

/**
 * Immutable; represents an if-then-else expression.
 *
 * <p> <b>Invariant:</b>  type!=EMPTY => (cond.mult==0 && left.mult==0 && right.mult==0)
 */

public final class ExprITE extends Expr {

    /** The condition formula. */
    public final Expr cond;

    /** The then-clause. */
    public final Expr left;

    /** The else-clause (if this ExprITE expression is unambiguously typedchecked, then this field is never null) */
    public final Expr right;

    /** Caches the span() result. */
    private Pos span=null;

    /** {@inheritDoc} */
    @Override public Pos span() {
        Pos p=span;
        if (p==null) span = (p = cond.span().merge(right!=null ? right.span() : null).merge(left.span()));
        return p;
    }

    /** {@inheritDoc} */
    @Override public void toString(StringBuilder out, int indent, boolean newline) {
    	for(int i=0; i<indent && newline; i++) { out.append(' '); }
            
        out.append('(');
        out.append("{");
        cond.toString(out,indent,false);
        out.append("}");
        out.append(" => ");
        left.toString(out, indent,false);
        if (right!=null) { out.append(" else\n"); right.toString(out,indent+2,true); }
        out.append(')');
    }

    /** Constructs a ExprITE expression. */
    private ExprITE(Pos pos, Expr cond, Expr left, Expr right, Type type, JoinableList<Err> errs) {
        super(pos, null, (cond.ambiguous || left.ambiguous || (right!=null && right.ambiguous)), type, 0, cond.weight+left.weight+(right!=null ? right.weight : 0), errs);
        this.cond=cond;
        this.left=left;
        this.right=right;
    }

    /**
     * Constructs a ExprITE expression.
     *
     * @param cond - the condition formula
     * @param left - the then-clause
     * @param right - the else-clause
     */
    public static Expr make(Pos pos, Expr cond, Expr left, Expr right) {
    	return new ExprITE(pos, cond, left, right, EMPTY, emptyListOfErrors);
    }

   
    /** {@inheritDoc} */
    public int getDepth() {
        int a = cond.getDepth(), b = left.getDepth(), c = right.getDepth();
        if (a>=b) return 1+(a>=c ? a : c); else return 1+(b>=c ? b : c);
    }

    /** {@inheritDoc} */
    @Override final<T> T accept(VisitReturn<T> visitor) throws Err { return visitor.visit(this); }
}
